An electromechanical power transmission chain comprises typically one or more electrical machines and an electronic power converter. The electromechanical power transmission chain can be a series transmission chain where one of the electrical machines operates as generator and the electronic power converter is arranged to convert the electrical voltages produced by the generator into electrical voltages having amplitudes and frequencies suitable for the one or more other electrical machines. The generator can be driven with a combustion engine that can be e.g. a diesel engine, an Otto-cycle engine, or a turbine engine. The other electrical machines can be, for example, electrical motors in wheels of a mobile working machine. The electronic power converter comprises typically an intermediate circuit, a converter stage between the generator and the intermediate circuit and one or more other converter stages between the intermediate circuit and the other electrical machines. Furthermore, there is usually a need for a converter stage between the intermediate circuit and an overvoltage protection resistor and for a converter stage between the intermediate circuit and an energy-storage such as a battery and/or a high capacitance capacitor. It is also possible that the electromechanical power transmission chain is a parallel transmission chain where the generator is occasionally used as a motor that assists the combustion engine, especially when high output power is needed. In this case, the electronic power converter comprises typically an intermediate circuit, a converter stage between the generator and the intermediate circuit, and one or more converter stages between the intermediate circuit and one or more energy-storages. Furthermore, also in conjunction with a parallel transmission chain, there is usually a need for a converter stage for controlling the operation of an overvoltage protection resistor.
As an electromechanical power transmission chain comprises typically many converter stages, energy-storages, and an overvoltage protection resistor, the number of components is high and, consequently, the arrangement of the components and cabling between the components may be complicated and space-consuming. Furthermore, the cooling arrangements related to the converter stages, energy-storages, and the overvoltage protection resistor may also be complicated and space-consuming because of the high number of objects to be cooled.
A typical way to increase the integration level is to use power electronic modules which have an integrated structure and comprise power electronic components so that, for example, a main circuit of the converter stage connected to a generator can be implemented with a single power electronic module. Typically, a power electronic module of the kind mentioned above comprises switching branches each of which comprising a first electrical node, a second electrical node, a third electrical node, and controllable power switches for selecting whether the third electrical node is connected to the first electrical node or to the second electrical node. As the number of phases of an alternating voltage system is typically three, a standard power electronic module contains three switching branches. Each controllable power switch may be, for example but not necessarily, an insulated gate bipolar transistor “IGBT” provided with an anti-parallel diode.
In spite of the power electronic modules of the kind described above, there are still challenges regarding to implementation, cabling, control, and/or cooling of other elements such as a capacitive energy-storage that is typically connected to an intermediate circuit with one or more electronic DC-to-DC power converters. Furthermore, there can be challenges regarding to cabling and/or cooling of one or more inductor coils which are typically parts of the above-mentioned electronic DC-to-DC power converters.